This invention relates to ion-exchange polymers and particularly, although not exclusively, relates to sulphonaced polymers, for example sulphonated polyaryletherketones, polyarylethersulphones and/or copolymers of the aforesaid. Preferred embodiments of the invention relate to ion-conductive membranes, for example of polymer electrolyte membrane fuel cells, made using such polymers. The invention also relates to novel, non-sulphonated polyaryletherketones and/or polyarylethersulphones used for preparing said sulphonated polymers and processes for the preparation of polymers described herein.
A polymer electrolyte membrane fuel cell (PEMFC), shown schematically in FIG. 1 of the accompanying diagrammatic drawings, may comprise a thin sheet 2 of a hydrogen-ion conducting Polymer Electrolyte Membrane (PEM) sandwiched on both sides by a layer 4 of platinum catalyst and an electrode 6. The layers 2, 4, 6 make up a Membrane Electrode Assembly (MEA) of less than 1 mm thickness.
In a PEMFC, hydrogen is introduced at the anode (fuel electrode) which results in the following electrochemical reaction:
Pt-Anode (Fuel Electrode) 2H2xe2x86x924H++4e 
The hydrogen ions migrate through the conducting PEM to the cathode. Simultaneously, an oxidant is introduced at the cathode (oxidant electrode) where the following electrochemical reaction takes place:
xe2x80x83Pt-Cathode (Oxidant Electrode) O2 +4H++4exe2x86x922H2O
Thus, electrons and protons are consumed to produce water and heat. Connecting the two electrodes through an external circuit causes an electrical current to flow in the circuit and withdraw electrical power from the cell.
U.S. Pat. No. 5,561,202 (Hoechst) discloses the production of PEMs from sulphonated aromatic polyether ketones. At least 5% of the sulphonic groups in the sulphonic acid moieties are converted into sulphonyl chloride groups and then reacted with an amine containing at least one cross-linkable substituent or a further functional group. An aromatic sulphonamide is, then isolated, dissolved in an organic solvent, converted into a film and then the cross-linkable substituents in the film are cross-linked. The invention is said to provide ion-conductive membranes suitable for use as polymeric solid electrolytes which have adequate chemical stability and can be produced from polymers which are soluble in suitable solvents.
One problem associated with known PEMFCs is that of providing PEMs which have desirable properties at elevated temperatures and which are cheap to manufacture.
It is an object of the present invention to address problems associated with PEMs.
According to a first aspect of the invention, there is provided a polymer electrolyte membrane which includes a polymer having a moiety of formula 
and/or a moiety of formula 
and/or a moiety of formula 
wherein at least some of the units I, II and/or III are sulphonated; wherein the phenyl moieties in units I, II, and III are independently optionally substituted and optionally cross-linked; and wherein m,r,s,t,v,w and z independently represent zero or a positive integer, E and Exe2x80x2 independently represent an oxygen or a sulphur atom or a direct link, G represents an oxygen or sulphur atom, a direct link or a xe2x80x94Oxe2x80x94Phxe2x80x94Oxe2x80x94 moiety where Ph represents a phenyl group and Ar is selected from one of the following moieties (i) to (x) which is bonded via one or more of its phenyl moieties to adjacent moieties 
The invention extends to a polymer electrolyte membrane which includes a polymer having a moiety of formula I and/or a moiety of formula II and/or a moiety of formula III as described according to said first aspect, wherein at least some of units I, II and/or III are functionalised to provide ion exchange sites. Suitably, to provide said ion exchange sites, said polymer is sulphonated, phosphorylated, carboxylated, quaternary-aminoalkylated or chloromethylated, and optionally further modified to yield xe2x80x94CH2PO3H2, xe2x80x94CH2NR320+ where R20 is an alkyl, or xe2x80x94CH2NAr3x+ where Arx is an aromatic (arene), to provide a cation or: anion exchange membrane. Further still, the aromatic moiety may contain a hydroxyl group which can be readily elaborated by existing methods to generate xe2x80x94OSO3H and xe2x80x94OPO3H2 cationic exchange sites on the polymer. Ion exchange sites of the type stated may be provided as described in WO95/08581.
References to sulphonation include a reference to substitution with a group xe2x80x94SO3M wherein M stands for one or more elements selected with due consideration to ionic valencies from the following group: H, NR4y+, in which Ry stands for H, C1-C4 alkyl, or an alkali or alkaline earth metal or a metal of sub-group 8, preferably H, NR4y+, Na, K, Ca, Mg, Fe, and Pt. Preferably M represents H. Sulphonation of the type stated may be provided as described in WO96/29360.
Unless otherwise stated in this specification, a phenyl moiety may have 1,4- or 1,3-, especially 1,4-, linkages to moieties to which it is bonded.
Said polymer may include more than one different type of repeat unit of formula I; more than one different type of repeat unit of formula II; and more than one different type of repeat unit of formula III.
Said moieties I, II and III are suitably repeat units. In the polymer, units I, II and/or III are suitably bonded to one anotherxe2x80x94that is, with no other atoms or groups being bonded between units I, II, and III.
Where the phenyl moieties in units I, II or III are optionally substituted, they may be optionally substituted by one or more halogen, especially fluorine and chlorine, atoms or alkyl, cycloalkyl or phenyl groups. Preferred alkyl groups are C1-10, especially C1-4, alkyl groups. Preferred cycloalkyl groups include cyclohexyl and multicyclic groups, for example adamantyl. In some cases, the optional substituents may be used in the cross-linking of the polymer. For example, hydrocarbon optional substituents may be functionalised, for example sulphonated, to allow a cross-linking reaction to take place. Preferably, said phenyl moieties are unsubstituted.
Another group of optional substituents of the phenyl moieties in units I, II or III include alkyls, halogens, CyF2y+1, where y is an integer greater than zero, Oxe2x80x94Rq (where Rq is selected from the group consisting of alkyls, perfluoralkyls and aryls), CFxe2x95x90CF2, CN, NO2 and OH. Trifluormethylated phenyl moieties may be preferred in some circumstances.
Where said polymer is cross-linked, it is suitably cross-linked so as to improve its properties as a polymer electrolyte membrane, for example to reduce its swellability in water. Any suitable means may be used to effect cross-linking. For example, where E represents a sulphur atom, cross-linking between polymer chains may be effected via sulphur atoms on respective chains. Alternatively said polymer may be cross-linked via sulphonamide bridges as described in U.S. Pat. No. 5,561,202. A further alternative is to effect cross-linking as described in EP-A-0008895.
However, for polymers according to the first aspect or second aspect which are crystalline (which some are) there may be no need to effect cross-linking to produce a material which can be used as a polymer electrolyte membrane. Such polymers may be easier to prepare: than cross-linked polymers. Thus, said polymer of the first and/or second aspects may be crystalline. Preferably, said polymer is not optionally cross-linked as described.
Where w and/or z is/are greater than zero, the respective phenylene moieties may independently have; 1,4- or 1,3-linkages to the other moieties in the repeat units of formulae II and/or III. Preferably, said phenylene moieties have 1,4- linkages.
Preferably, the polymeric chain of the polymer does not include a xe2x80x94Sxe2x80x94 moiety. Preferably, G represents a direct link.
Suitably, xe2x80x9caxe2x80x9d represents the mole % of units of formula I in said polymer, suitably wherein each unit I is the same; xe2x80x9cbxe2x80x9d represents the mole % of units of formula II in said polymer, suitably wherein each unit II is the same; and xe2x80x9ccxe2x80x9d I represents the mole % of units of formula III in said polymer, suitably wherein each unit III is the same. Preferably, a is in the range 45-100, more preferably in the range 45-55, especially in the range 48-52. Preferably, the sum of b and c is in the range 0-55, more preferably in the range 45-55, especially in the range 48-52. Preferably, the ratio of a to the sum of b and c is in the range 0.9 to 1.1 and, more preferably, is about 1. Suitably, the sum of a, b and c is at least 90, preferably at least 95, more preferably at least 99, especially about 100. Preferably, said polymer consists essentially: of moieties I, II and/or III.
Said polymer may be a homopolymer having a repeat unit of general formula 
or a homopolymer having a repeat unit of general formula. 
or a random or block copolymer of at least two different units of IV and/or V
wherein A, B. C and D independently represent 0 or 1 and E,Exe2x80x2, G,Ar,m,r,s,t,v,w and z are as described in any statement herein.
As an alternative to a polymer comprising units IV and/or V discussed above, said polymer may be a homopolymer having a repeat unit of general formula 
or a homopolymer having a repeat unit of general formula 
or a random or block copolymer of at least two different units of IV* and/or V*, wherein A, B, C, and D independently represent 0 or 1 and E, Exe2x80x2, G, Ar, m, r, s, t, v, w and z are as described in any statement herein.
Preferably, m is in the range 0-3, more preferably 0-12, especially 0-1. Preferably, r is in the range 0-3, more preferably 0-2, especially 0-1. Preferably t is in the range 0-3, more preferably 0-2, especially 0-1. Preferably, s is 0 or 1. Preferably v is 0 or 1. Preferably, w is 0 or 1. Preferably z is 0 or 1.
Preferably Ar is selected from the following moieties (xi) to (xxi): 
Preferably, (xv) is selected from a 0.1,2-, 1,3-, or a 1,5-moiety; (xvi) is selected from a 1,6-, 2,3-, 2,6- or a 2,7-moiety; and (xvii) is selected from a 1,2-, 1,4-, 1,5-, 1,8- or a 2,6- moiety.
One preferred class of polymers may include at least some ketone moieties in the polymeric chain. In such a preferred class, the polymer preferably does not! only include xe2x80x94Oxe2x80x94 and xe2x80x94SO2xe2x80x94 moieties between aryl (or other unsaturated) moieties in the polymeric chain. Thus, in this case, suitably, a polymer of the first and/or second aspects does not consist only of moieties of formula; III, but also includes moieties of formula I and/or II.
One preferred class of polymers does not include any moieties of formula III, but suitably only includes moieties of formulae I and/or II. Where said polymer is a homopolymer or random or block copolymer as described, said homopolymer or copolymer suitably includes a repeat unit of general formula IV. Such a polymer may, in some embodiments, not include any repeat unit of general formula V.
Referring to formula IV, preferably, said polymer is not a polymer wherein: Ar represents moiety (iv), E and Exe2x80x2 represent oxygen atoms, m represents zero, w represents 1, s represents zero, and A and B represent 1; Ar represents moiety (i), E and Exe2x80x2 represent oxygen atoms, G represents a direct link, m represents zero, w represents 1, r represents O, s represents 1 and A and B represent 1; A Ar represents moiety (iv), E and Exe2x80x2 represent oxygen atoms, G represents a direct link, m represents O, w represents O, s represents 1, r represents 1 and A and B represents 1. Referring to formula V, preferably Ar represents moiety (iv), E and Exe2x80x2 represent oxygen atoms, G represents a direct link, m represents zero, z represents 1, v represents zero and C and D represent 1.
Preferably, said polymer is not a sulphonated aromatic polyecherketone of formula
xe2x80x94[[Phxe2x80x94O]pxe2x80x94Phxe2x80x94[[COxe2x80x94Phxe2x80x2]xxe2x80x94Oxe2x80x94Ph]hxe2x80x94[COxe2x80x94Phxe2x80x2]yxe2x80x94[Oxe2x80x94Ph]nxe2x80x94COxe2x80x94]xe2x80x94
where Ph represents a 1,4- or 1,3-phenylene moiety; Phxe2x80x2 represents phenylene, naphthylene, biphenylene or anthrylene; p is 1, 2, 3 or 4; x, h and n are, independently, zero or 1; and y is 1, 2 or 3.
Preferably, said polymer does not conform to the formula 
where
e is from 0.2 to 1,
f is from 0 to 0.8, and
e+f=1
Preferably, said polymer does not conform to the formula 
in which e is a number from 0 to 1, g is a number from 0 to 1, f is a number from 0 to 0.5, and the sum e+f+g=1.
Preferably, said polymer is not a copolymer built up from at least two different units of formulae: 
Suitable moieties Ar are moieties (i), (ii) (iv) and (v) and, of these, moieties (i), (ii) and (iv) are preferred. Preferred moieties Ar are moieties (xi), (xii), (xiv), (xv) and (xvi) and, of these, moieties (xi), (xii) and (xiv) are especially preferred. Another preferred moiety is moiety (v), especially, moiety (xvi). In relation, in particular to the alternative polymers comprising units IV* and/or V*, preferred Ar moieties are (v) and, especially, (xvi).
Preferred polymers include an electron-rich, relatively non-deactivated, easily sulphonatable unit, for example a multi-phenylene moiety or a fused-rings aromatic moiety, such-as naphthalene. Such an easy to sulphonate unit may be sulphonated under relatively mild conditions to introduce two sulphonate groups per unit. Thus, preferred polymers may have at least 10n electrons in a delocalized aromatic moiety. The number of 90 electrons may be 12 or less. Preferred polymers include a biphenylene moiety. Other preferred polymers include a naphthalene moiety. Preferred polymers include said electron rich, non-deactivated, easily sulphonatable unit bonded to two oxygen atoms. Especially preferred polymers include a xe2x80x94O-biphenyllene-Oxe2x80x94 moiety. especially preferred polymers include a xe2x80x94O-naohthalene-Oxe2x80x94 moiety.
Preferred polymers include a first type of moiety which is relatively difficult to sulphonate and a second type of moiety which is relatively easy to sulphonate. For example, said second moiety may be sulphonatable using the relatively mild method described in Example 13 hereinafter, whereas the first moiety may be substantially non-sulphonatable in such a method. The use of the method of Example 13 may be advantageous over currently used methods which use oleum. A preferred second said moiety includes a imoiety xe2x80x94Phnxe2x80x94 wherein n is an integer of at least 2. Said moiety is preferably bound to at least one ether oxygen. Especially preferred is the case wherein said moiety is xe2x80x94Oxe2x80x94Phnxe2x80x94Oxe2x80x94 where said ether groups are para to the Phxe2x80x94Ph bond.
Preferred polymers are copolymers comprising a first repeat unit which is selected from the following:
(a) a unit of formula IV wherein E and Exe2x80x2 represent oxygen atoms, G represents a direct link, Ar represents a moiety of structure (iv), m and s represent zero, w represents 1 and A and B represent 1;
(b) a unit of formula IV wherein E represents an oxygen tom, Exe2x80x2 represents a direct link, Ar represents a moiety of structure (i), m represents zero, A represents 1, B represents zero;
(c) a unit of formula V wherein E and Exe2x80x2 represent oxygen atoms, G represents a direct link, Ar represents a moiety of structure (iv), m and v represent zero, z represents 1 and C and D represent 1;
(d) a unit of formula V wherein E represents an oxygen atom, Exe2x80x2 represents a direct link, Ar represents a moiety of structure (ii), m represents 0, C represents 1, D represents 0; or
(e) a unit of formula V wherein E and Exe2x80x2 represents an oxygen atom, Ar represents a structure (i), m represents 0, C represents 1, Z represents 1, G represents a direct link, v represents 0 and D represents 1;
and a second repeat unit which is selected from the following:
(f) a unit of formula IV wherein E and Exe2x80x2 represent oxygen atoms, G represents a direct link, Ar represents a moiety of structure (iv), m represents 1, w represents 1, s represents zero, A and B represent 1;
(g) a unit of formula IV wherein E represents an oxygen atom, Exe2x80x2 is a direct link, G represents a direct link, Ar represents a moiety of structure (iv), m and s represent zero, w represent 1, A and B represent 1;
(h) a unit of formula V wherein E and Exe2x80x2 represent oxygen atoms, G represents a direct link, Ar represents a moiety of structure (iv), m represents 1, z represents 1, v represents 0, C and D represent 1; and
(i) a unit of formula V wherein E represents an oxygen atom, Exe2x80x2 represents a direct link, G represents a direct link, Ar represents a moiety of structure (iv), mland v represent zero, z represents 1, C and D represent 1;
Other second units which may form copolymers with any of said first repeat units (a) to (e) above include: a unit of formula IV wherein E and Exe2x80x2 represent oxygen atoms, G represents a direct link, Ar represents a moiety of structure (v), m represents 0, w represents 1, s represents 0, A and B represent 1; or a unit of formula V wherein E and Exe2x80x2 represent oxygen atoms, G represents a direct link, Ar represents a moiety of structure (v), m represents: 0, z represents 1, v represents 0, C and: D represent 1.
Preferred polymers for some situations may comprise first units selected from (a), (b), (c) and (e) and second units selected from (f), (g), (h) or (i). A polymer. comprising units (d) and (h) may also be preferred.
More preferred polymers are copolymers having a first repeat unit selected from those described above, especially repeat units (b), (d) or (e) in combination with a second repeat unit selected from units (f) or (h).
Preferred polymers having repeat unit(s) of formulae IV* and V* may include: a unit of formula IV* wherein Ar represents a moiety of structure (v), E represents a direct link, Exe2x80x2 represents an oxygen atom, G represents a direct link, w, s and m represent 0, A and B represent 1; and/or a repeat unit of formula. V* wherein Ar represents a moiety of structure (v), E represents a direct link, Exe2x80x2 represents an oxygen atom, G represents a direct link, z, v and m represent 0, C and D represent 1.
Said polymers having repeat units IV* and V* may include any of repeat units (a) to (i) described above.
In some situations, polymers which include at least one repeat unit of formula IV or formula IV* may be preferred.
Copolymers may be prepared having one or more first repeat units and one or more of said second repeat units.
Where said polymer is a copolymer as described, the mole % of co-monomer units, for example said first and second repeat units described above, may be varied to vary the solubility of the polymer in solvents, for example in organic solvents which may be used in the preparation of films and/or membranes from the polymers and/or in other solvents, especially water.
Preferred polymers suitably have a solubility of at least 10% w/v, preferably a solubility in the range 10 to 30% w/v in a polar aprotic solvent, for example NMP, DMSO or DMF. Preferred polymers are substantially insoluble in boiling water.
First units of the type described above (with, the exception of units (a) and (c)) may be relatively difficult to sulphonate, whereas second units of the type described may be easier to sulphonate.
Where a phenyl moiety is sulphonated, it may only be mono-sulphonated. However, in some situations it may be possible to effect bi- or multi-sulphonation.
In general terms, where a said polymer includes a xe2x80x94O-phenyl-Oxe2x80x94 moiety, up to 100 mole % of the phenyl moieties may be sulphonated. Where a said polymer includes a xe2x80x94O-biphenylene-Oxe2x80x94 moiety, up to 100 mole % of the phenyl moieties may be sulphonated. It is believed to be possible to sulphonate relatively easily xe2x80x94O-(phenyl)nxe2x80x94Oxe2x80x94 moieties wherein n is an integer, suitably 1-3, at up to 100 mole %. Moieties of formula xe2x80x94O-(phenyl)nxe2x80x94COxe2x80x94 or xe2x80x94O-(phenyl)nxe2x80x94SO2xe2x80x94 may also be sulphonated at up to 100 mole % but more vigorous conditions may be required. Moieties of formulae xe2x80x94CO-(phenyl)nxe2x80x94COxe2x80x94 and xe2x80x94SO2-(phenyl)nxe2x80x94SO2xe2x80x94 are more difficult to sulphonate and may be sulphonated to a level less than 100 mole % or not at all under some sulphonation conditions.
The glass transition temperature (Tg) of said polymer may be at least 144xc2x0 C., suitably at least 150xc2x0 C., preferably at least 154xc2x0 C., more preferably at least 160xc2x0 C., especially at least 164xc2x0 C. In some cases, the Tg may be at least 170xc2x0 C., or at least 190xc2x0 C. or greater than 250xc2x0 C. or even 300xc2x0 C.
Said polymer may have an inherent viscosity (IV) of at least 0.1, suitably at least 0.3, preferably at least 0.4, more preferably at least 0.6, especially at least 0.7 (which corresponds to a reduced viscosity (RV) of least 0.8) wherein RV is measured at 25xc2x0 C. on a solution of the polymer in concentrated sulphuric acid of density 1.84 gcmxe2x88x923, said solution containing 1 g of polymer per 100 cmxe2x88x923 of solution. IV is measured at 25xc2x0 C. on a solution of polymer in concentrated sulphuric acid of density 1.84 gcm3, said solution containing 0.1 g of polymer per 100 cm3 of solution.
The measurements of both RV and IV both suitably employ a viscometer having a solvent flow time of approximately 2 minutes.
The main peak of the melting endotherm (Tm) for said polymer (if crystalline) may be at least 300xc2x0 C.
In general terms, said polymer is preferably substantially stable when used as a PEM in a fuel cell. Thus, it suitably has high resistance to oxidation, reduction and hydrolysis and has very low permeability to reactants in the fuel cell. Preferably, however, it has a high proton conductivity. Furthermore, it suitably has high mechanical strength and is capable of being bonded to other components which make up a membrane electrode assembly.
Said polymer may comprise a film, suitably having a thickness of less than 1 mm, preferably less than 0.5 mm, more preferably less than 0.1 mm, especially less than 0.05 mm. The film may have a thickness of at least 5xcexcm.
Said polymer electrolyte membrane may comprise one or more layers wherein, suitably, at least one layer comprises a film of said polymer. Said membrane may have a thickness of at least 5xcexcm and, suitably, less than 1 mm, preferably less than 0.5 mm, more preferably less than 0.1 mm, especially less than 0.05 mm.
The polymer electrolyte membrane may be a composite membrane which suitably includes a support material for the conductive polymer for importing mechanical strength and dimensional stability to the membrane. The polymer may be associated with the support material to form a composite membrane in a variety of ways. For example, an unsupported conductive polymer film can be preformed and laminated to the support material. Alternatively, (and preferably) the support material may be porous and a solution of the conductive polymer can be impregnated into the support material. In one embodiment, the support material may comprise, or preferably consist essentially of, polytetrafluoroethylene, suitably provided as a porous film. Such a support material may be as described and used in accordance with the teachings of WO97/25369and WO96/28242, the contents of which are incorporated herein by reference. Suitably, the support material has a porous microstructure of polymeric fibrils and is impregnated with said polymer throughout the material, preferably so as to render an interior volume of the membrane substantially occlusive.
The use of support material as described may allow polymers of lower equivalent weights (EW) (for example less than 500 g/mol, less than 450 g/mol or even less than 400 g/mol or 370 g/mol) or relatively inflexible and/or brittle polymers to be used in polymer electrolyte membranes.
The polymer electrolyte membrane suitably includes a layer of a catalyst material, which may be a platinum catalyst (i.e. platinum containing) or a mixture of platinum and ruthenium, on both sides of the polymer film. Electrodes may be provided outside the catalyst material.
It may be preferable for each phenyl group in a sulphonated polymer as described to be deactivated by being bonded directly to an electron withdrawing group, for example a sulphonated group, a sulphone group or a ketone group.
According to a second aspect of the invention, there is provided a polymer electrolyte membrane which includes a polymer which includes: polyaryletherketone and/or polyarylethersulphone units; and units of formula xe2x80x94OPhnxe2x80x94Oxe2x80x94 (XX) wherein Ph represents a phenyl group and n represents an integer of 2 or greater and wherein Ph groups of units (XX) are sulphonated.
Preferably, each phenyl group of moiety Phn is sulphonated, preferably mono-sulphonated. About 100 mole % of such phenyl groups may be sulphonated as described.
Preferably, xe2x80x94OPhCOxe2x80x94 and/or xe2x80x94OPhSO2xe2x80x94 moieties of said polymer are sulphonated to a lesser extent than the phenyl groups of moiety Phn. Moieties xe2x80x94OPhCOxe2x80x94 and xe2x80x94OPhSO2xe2x80x94 may be substantially non-sulphonated.
In one embodiment, said polymer may include no ketone linkages and may have an equivalent weight of more than 900. Nonetheless, it has been found, surprisingly, that such polymers are still conducting.
Said polymer electrolyte membrane may be for a fuel cell or an electrolyser.
The invention extends to the use of a polymer which includes relatively easy to sulphonate units and relatively difficult to sulphonace units in the preparation of a polymer for a polymer electrolyte membrane.
The polymer electrolyte membrane described herein may include a blend of polymers, at least one of which is a polymer described according to the invention described herein. Suitably the polymers described herein are blended with 0-40wt %, preferably 0-20wt %, more preferably 0-10wt %, especially 0xe2x80x945wt % of other polymeric material. Preferably, however, a blend of polymers is not provided.
According to a third aspect of the invention, there is provided a fuel cell or an electrolyser (especially a fuel cell) incorporating a polymer electrolyte membrane according to the first or second aspects.
According to a fourth aspect of the invention, there is provided any novel polymer as described according to said first aspect per se.
According to a fifth aspect of the invention, there is provided a process for the preparation of a polymer as described in the first, second, third and/or fourth aspects, the process comprising:
(a) polycondensing a compound of general formula 
with itself wherein Y1 represents a halogen atom or a group xe2x80x94EH and y2 represents a halogen atom or, if y1 represents a halogen atom, Y2 represents a group Exe2x80x2H; or
(b) polycondensing a compound of general formula 
with a compound of formula 
and/or with a compound of formula 
wherein Y1 represents a halogen atom or a group xe2x80x94EH (or Exe2x80x2 H if appropriate) and X1 represents the other one of a halogen atom or group xe2x80x94EH (or xe2x80x94Exe2x80x2H if appropriate) and Y2 represents a halogen atom or a group xe2x80x94Exe2x80x2 H and X2 represents the other one of a halogen atom or a group xe2x80x94Exe2x80x2 H (or xe2x80x94EH if appropriate).
(c) optionally copolymerizing a product of a process as described in paragraph (a) with a product of a process as described in paragraph (b);
wherein the phenyl moieties of units VI, VII and/or VIII are optionally substituted; the compounds VI, VII and/or VIII are optionally sulphonated; and Ar, m, w, r, s, z, t, v, G, E and Exe2x80x2 are as described above except that E and Exe2x80x2 do not represent a direct link;
the process also optionally comprising sulphonating and/or cross-linking a product of the reaction described in paragraphs (a), (b) and/or (c) to prepare said polymer.
In some situations, the polymer prepared, more particularly phenyl groups thereof, may be optionally substituted with the groups hereinabove described after polymer formation.
Preferably, where Y1, Y2, X1 and/or X2 represent a halogen, especially a fluorine, atom, an activating group, especially a carbonyl or sulphone group, is arranged ortho- or para- to the halogen atom.
Advantageously, where it is desired to prepare a copolymer comprising a first repeat unit IV or V wherein E represent an oxygen or sulphur atom, Ar represents a moiety of structure (i), m represents zero, Exe2x80x2 represents a direct link, A represents 1 and B represents zero and a second repeat unit IV or V wherein E and Exe2x80x2 represent an oxygen or sulphur atom, Ar represents a moiety of structure (iv), m and w represent 1, G represents a direct link, s represents zero and A and B represent 1 wherein the polymer is not a random polymer but has a regular structure, the process described in paragraph (b) above may be used wherein in said compound of general formula VI, Y1 and y2 represent xe2x80x94OH or xe2x80x94SH groups, Ar represents a moiety of structure (iv) and m represents 1 and in said compounds of general formulae VII and VIII, X1 and X2 represent a fluorine atom, w,r,s,z,t and v represent 1 and G represents an oxygen or sulphur atom.
In another embodiment, where it is desired to prepare a copolymer comprising a first repeat unit IV or V wherein E and Exe2x80x2 represent an oxygen or sulphur atom, Ar represents a moiety of structure (iv), m represents zero, A represents 1, w represents 1, s represents zero and B represents: 1 and a second repeat unit IV or V wherein E and Exe2x80x2 represent an oxygen or sulphur atom, Ar represents a moiety of structure (iv), m and w represent 1, s represents zero and A and B represent 1, wherein the polymer is not a random polymer but has a regular structure, the process described in paragraph (b) above may be used wherein in said compound of general formula VI, Y1 and Y2 represent xe2x80x94OH or xe2x80x94SH groups, Ar represents a moiety of structure (iv) and m represents 1 and in said compounds of general formulae VII and VIII, X1 and X2 represent a fluorine atom, w,r,s,z,t and v represent 1 and G represents a xe2x80x94Oxe2x80x94Phxe2x80x94Oxe2x80x94 moiety.
Preferred halogen atoms are fluorine and chlorine atoms, with fluorine atoms being especially preferred. Preferably, halogen atoms are arranged meta- or para- to activating groups, especially carbonyl groups.
Where the process described in paragraph (a) is carried out, preferably one of Y1 and Y2 represents a fluorine atom and the other represents an hydroxy group. More preferably in this case, Y1 represents a fluorine atom and Y2 represents an hydroxy group. Advantageously; the process described in paragraph (a) may be used when Ar represents a moiety of structure (i) and m represents 1.
When a process described in paragraph (b) is carried out, preferably, Y1 and Y2 each represent an hydroxy group. Preferably, X1 and X2 each represent a halogen atom, suitably the same halogen atom.
Compounds of general formula VI, VII and VIII are commercially available (eg from Aldrich U.K.) and/or may be prepared by standard techniques, generally involving is Friedel-Crafts reactions, followed by appropriate derivatisation of functional groups. The preparations of some of the monomers described herein are described in P M Hergenrother, B J Jensen and S J Havens, Polymer 29, 358 (1998), H R Kricheldorf and U Delius, Macromolecules 22, 517 (1989) and P A Staniland, Bull, Soc, Chem, Belg., 98 (9-10), 667 (1989)
Where compounds VI, VII and/or VIII are sulphonated, compounds of formulas VI, VII and/or VIII which arel not sulphonated may be prepared and such compounds may be sulphonated prior to said polycondensation reaction.
Sulphonation as described herein may be carried oust in concentrated sulphuric acid (suitably at least 96% w/w, preferably at least 97% w/w, more preferably at least 98% w/w; and preferably less than 98.5% w/w) at an elevated temperature. For example, dried polymer may be contacted with sulphuric acid and heated with stirring at a temperature of greater than 40xc2x0 C., preferably greater than 55xc2x0 C., for at least one hour, preferably at least two hours, more preferably about three hours. The desired product may be caused to precipitate, suitably by contact with cooled water, and isolated by standard techniques. Sulphonation may also be effected as described in U.S. Pat. No. 5,362,836 and/or EP0041780.
Where the process described in paragraph (b) is carried out, suitably, xe2x80x9ca*xe2x80x9d represents the mole % of compound VI used in the process; xe2x80x9cb*xe2x80x9d represents the mole % of compound VII used in the process; and xe2x80x9cc*xe2x80x9d represents the mole % of compound VIII used in the process.
Preferably, a* is in the range 45-55, especially in the. range 48-52. Preferably, the sum of b* and c* is in the range 45-55, especially in the range 48-52. Preferably, the sum of a*, b* and c* is 100.
Where the process described in paragraph (b) is carried out, preferably, one of either the total mole % of halogen atoms or groups xe2x80x94EH/xe2x80x94Exe2x80x2H in compounds VI, VII and VIII is greater, for example by up to 10%, especially up to 5%, than the total mole % of the other one of either the total mole % of halogen atoms or groups xe2x80x94EH/xe2x80x94Exe2x80x2H in compounds VI, VII and VIII. Where the mole % of halogen atoms is greater, the polymer may have halogen end groups and be more stable than when the mole % of groups xe2x80x94EH/xe2x80x94Exe2x80x2H is greater in which case the polymer will have xe2x80x94EH/xe2x80x94Exe2x80x2H end groups. However, polymers having xe2x80x94EH/xe2x80x94Exe2x80x2H end groups may be advantageously cross-linked.
The molecular weight of the polymer can also be controlled by using an excess of halogen or hydroxy reactants. The excess may typically be in the range 0.1 to 5.0 mole %. The polymerisation reaction may be terminated by addition of one or more monofunctional reactants as end-cappers.
It is believed that certain polymers described herein are novel and, therefore, in a sixth aspect, the invention extends to any novel polymer described herein per se.
It is also believed that certain polymers according to said first and/or second aspect but which are; not sulphonated are novel. Thus, according to a seventh aspect of the invention, there is provided a novel polymer having a moiety of formula I and/or a moiety of formula II and/or a moiety of formula III wherein ,E,Exe2x80x2, G,m,r,s,t,v,w,z and Ar are as described in any statement herein.
Preferably, said polymer includes a moiety of formula II and/or III and Ar is selected from 
Preferably, in the aforementioned formulae, each xe2x80x94Arxe2x80x94 is bonded to adjacent moieties as described in any statement herein.
According co an eighth aspect of the invention, there is provided a process for the preparation of novel polymers according to said seventh aspect, the process being as described according to the process of the fifth aspect except that compounds VI, VII and VIII are not sulphonated and the process does not include a sulphonation step.
Sulphonated polymers described herein may be made into films and/or membranes for use as PEMs by conventional techniques, for example as described in Examples 5 to, 7 of U.S. Pat. No. 5,561,202.
The sulphonated polymers described herein may be used as polymer electrolyte membranes in fuel cells or electrolysers as described. Additionally, they may be used in gas diffusion electrodes.
Any feature of any aspect of any invention or example described herein may be combined with any feature of any aspect of any other invention or example described herein.